27 lines
578 B
Markdown
27 lines
578 B
Markdown
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## Execution Mode
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Starts in Real Mode
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# Real Mode
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- 16 bit
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- 20 bit segmented memory
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- Max 1 MB memory
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- Direct access to peripherals
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- No memory protection or multitasking
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- BIOS computers start in this mode
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# Protected Mode
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- 16 bit & 32 bit
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- Max 16 MB of physical memory
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- Max 1 GB virtual memory
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- Privilege levels and protected memory
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# Long Mode
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- 64 bit
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- Largely an extension to 32 bit protected mode
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# System Management Mode
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- 16 bit
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- System-wide functions
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- Power management
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- System control hardware
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- Proprietary OEM code
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